Telecommunication shelters or enclosures are often located in remote areas. These shelters are typically cooled by on-site electrically powered air conditioning systems, which maintain the interior temperature below that which would cause the telecommunication system to shut down or otherwise fail or compromise reliable operations. Other shelters for electronic equipment such as military sites, outposts or FEMA equipment locations that house temperature sensitive electronic components for military, surveillance, detection or other applications may also be located such that access to convenient electrical power from a power grid is limited, or even unavailable.
In locations where grid power is unavailable or unreliable, AC power may be provided by generators. However, if AC power is lost, without adequate, immediate, power back-up, temperature-sensitive systems may shut down operations if the temperature inside the shelter rises above a certain threshold. This can lead to significant damage of sensitive computer equipment.
Although battery back-up systems are provided for many applications, such back-up is typically used only for operating the electronic or telecommunications equipment, and may be insufficient for providing power to air conditioning systems because of limited battery power output.